User's Manual

012–07192A Discover Density Set
13
Introduction
In this activity you are given four transparent plastic spheres of different
diameters. You are asked to take data, organize it, graph it, and create an
equation relating the mass and diameter of the spheres. A minimum of
instructions are given. You should study and follow the example titled “The
Mass of Fluorite Octahedra,” which preceded this task.
Materials
The materials needed are in compartments C3, C4, C5, and C6.
Procedure
1. Create a table to record the diameter and mass of the four spheres.
Record the diameter in centimeters. If you are using a metric ruler,
estimate to the nearest 0.01 cm when finding these dimensions. You
should use two rectangular objects with the ruler to increase your
accuracy. (See Figure 6.) Use the rules regarding significant figures or
other appropriate methods of expressing uncertainty.
Finding an
Equation
Relating
Mass and
Diameter
of
Transparent
Plastic
Spheres
TOP VIEW
rectangular solids
sphere
ruler
2. Consider the diameter to be the independent variable, and the mass to
be the dependent variable when graphing the data. Prepare a graph that
shows the data for all four spheres.
3. Draw a best-fit line for the data, which may be a smooth curve. If it is
not possible to represent the data well with a smooth curve, recheck
your measurements for any data points that do not fit the pattern.
4. State a hypothesis regarding the form of equation that is likely to best
describe the data.
5. Determine an equation that represents the data. Use one or more of the
methods outlined in the example, “The mass of fluorite octahedra.”
Figure 6
Using the rectangular
solids to increase the
accuracy of the
measurement of the
diameter of a cylinder